Many ancient sources mention various medical treatments by means of minerals, plants and stones. One of the most famous sources is the Natural History of Pliny the Elder. De materia medica “on medical material” of Pedanius Dioscurides has been effectively used until the 16th century, being considered one of the most important reference sources. The writings of the physician Galenos are immensely large, presenting an immeasurable contribution to the science of medicine. In later period Oribasios, the physician of Julian, and Aetios, who was educated in Alexandria, continued the tradition of their predecessors in medicine. The reason why only these ancient authors are mentioned here is that they all provide information on an interesting stone, which is reported as able to drive serpents away, diagnose epilepsy, calm the women down in their hysterias, evacuate worms, ease heart problems, heal the gynaecological diseases, is used as an ornament for jewellery and has many other uses, i. e. λ?θος γαγ?της – The Stone of Gagates. This stone is important for the region of Antalya, because it was recorded by ancient authors that this stone was found by the estuary of a river called “Gages” near to Gagai in Lycia and named after this river. 
The stone is described as a modern jet stone, which fits perfectly with ancient descriptions. Although it is a form of lignite, containing bitumen and petroleum, it is not used for heating. In Anatolia, the most similar stone to Gagates is the Oltu Taşı, mined in Erzurum. Apart from Turkey, this form of stone can be found in, Russia, Germany, France, Spain, Portugal, North America and Britain. 
Unfortunately there has been no evidence found to date concerning the stone and the river around Gagai, though there are suggestions for Gages as it may be the ancient name of the Alakır Çay or Gavur Çayı. Intensive research conducted around this area will almost certainly enlighten us on this issue of the location of Gages River and Gagates mine.